But Arriva says it wants to hold constructive discussions with the union about introducing driver controlled trains on parts of its network.

The company said it will run almost 1,400 services today, with the majority operating between 7am and 7pm.

"The overall number of trains running will be reduced, we expect trains and any replacement buses operate to be extremely busy," it said. "Please allow extra time for journeys, plan carefully and consider whether travel is necessary.

"During the RMT strike action we expect all services to be busy, especially in the morning and evening peak periods, and advise you to allow extra time to travel."